Apparatus and method for enhanced oil recovery
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to injecting one or more phases of steam into one or more formations from a single string of tubing by utilizing an impingement means in a side pocket mandrel or other downhole tools and including, if desired, an agitation device to control the quality and flow of steam. The invention may also include a centralizer to guide a tool string and disperse the steam. 
     2. Description of Related Art 
     In the past, various configurations of devices were used to inject steam and other fluids and gases into one or more zones of a formation to enhance hydrocarbon recovery, such as oil, from the earth. Depending on the medium injected and the properties of the formation, some of these devices were more successful than others. 
     Early injection techniques usually involved drilling a hole for each formation zone in a selected area. This horizontal expansion method of enhanced recovery is extremely expensive and time-consuming. A more economical method would entail servicing the various zones in a formation by way of multiple injection points in a single drilled hole. 
     A related patent, U.S. Pat. No. 4,248,302, answering the need for multiple zone injection from a single drilled hole was granted to Ronald K. Churchman and was assigned to Otis Engineering Corporation. Although particularly addressing pumpdown (through the flow line) completions, the patent does show using one or more side pocket mandrels to inject fluids and steam into one or more wells and/or formation zones. This method and apparatus was an advancement in the field of steam injection. 
     As interest in injection increased, several zones in a formation were serviced from a single drilled hole by utilizing concentric tubing. Such a configuration is shown in U.S. Pat. No. 3,319,717 by D. V. Chenoweth, U.S. Pat. Nos. 4,081,032, 4,099,563 and 4,399,865 by S. O. Hutchinson and G. W. Anderson and U.S. Pat. No. 4,081,028 by E. E. Rogers. All these devices allow steam or hot fluids to flow through the inner tubing to the next distributing apparatus while providing a passage for the steam or hot fluids to flow into the casing-tubing annulus and into a selected zone. While an improvement on multiwells, these devices did not allow the operator to deliver a calculated percentage of steam and hot fluid to a particular zone nor did they control the quality of the steam at several points in the well bore. Also the operator could not run maintenance tools down the tubing string to rework the downhole devices. Testing of this type of device showed that heat transfer between the concentric tubes created a heat loss from one tube to the other and created undesirable tubing movement. Chenoweth&#39;s U.S. Pat. No. 3,319,717 device was retrievable but had to be removed from the tubing string before any survey or maintenance tools could be run below the device. Oilfield operators wanted a system more controllable and more easily maintained. 
     U.S. Pat. No. 3,455,382 by D. V. Chenoweth solved part of the maintenance problem by injecting into different zones with a pressure regulator placed in a side pocket material. Tools to service the downhole devices could then be passed by the pressure regulators without removing them. The function of the pressure regulators was to keep the single phase injection fluids going through the exit port in the side pocket mandrel and into the tubing-casing annulus at a constant rate regardless of tubing pressure upstream or downstream of the pressure regulator. However, Chenoweth&#39;s device did not address the problem of providing a desired percentage of vapor and hot fluids to one or more separate formation zones. This device did not, because of its throttle-like action, allow the user to calculate a critical flow relationship utilizing known input pressures of injected fluid or steam. The present invention does allow the user to calculate a critical flow relationship and also has the advantage of having no moving parts. 
     SUMMARY OF THE INVENTION 
     The present invention includes an impingement means and other means within the flow passageway of a side pocket mandrel or other downhole tools to mix and direct the flow of steam and inject the steam into the formation. Steam is defined throughout this application to mean vapor and hot fluid or any combination thereof unless addressed separately as hot fluid or vapor. The steam is used to aid in the recovery of viscous petroleums, usually on the order of one to 1,000,000 centipoise at reservoir temperatures, by heating the petroleum with the steam. 
     The side pocket mandrel or other downhole tool is connected to a source of pressurized steam. The steam is pumped under pressure to the side pocket mandrel or other downhole tools through flow conductors. The steam as it leaves the source is mostly of a vaporous nature. As it travels through the flow conductors, it has a tendency to separate into a combination of vapor and hot fluid. A portion of this hot fluid including some vapor clings to the wall of the flow conductor in a more or less laminar manner while the remaining vapor continues down the center of the flow conductors. 
     In order to recombine the vapor and the hot fluid into a desired percentage of each, the impingement means mixes the two phases. This is accomplished in a chamber formed between the impingement means and the wall of the longitudinal flow passageway of the side pocket mandrel or other downhole tools. Primarily, hot fluid enters the grooves of the impingement means and is directed through the chamber formed by the impingement means and the wall of the longitudinal flow passageway of the side pocket mandrel body or other downhole tools by way of the radial directing means which in the preferred embodiment is a spirally-cut set of lands and grooves. The vapor phase of the steam flows into and is deflected by the fingers of the impingement means into the longitudinal flow passageway of the impingement means. These fingers also serve to guide tools through the impingement means. One or more holes through the wall in the impingement means allow the vapor to enter grooves formed on the outside diameter of the impingement means and the chamber formed between the outside diameter of the impingement means and the wall of the longitudinal flow passageway of the side pocket mandrel body or other downhole tools. 
     After mixing a percentage of the steam enters a value means which regulates the flow of steam into the tubing-casing annulus and into the formation zone through the perforations or flows out through drain holes in the impingement means to continue down toward other downhole equipment. The valve means could be, among other devices, a choke means. In the preferred embodiment, an offset choke means referred to as a valve means is used. Vapor and hot fluid that did not enter the chamber, as described above, flow through the longitudinal flow passageway and on to other downhole equipment. 
     The present device injects a preferred percentage of hot fluid and vapor into the formation zones at preselected intervals thus warming the viscous petroleum and enhancing its flow characteristics. 
     The impingement means can be placed in a downhole tool, other than a side pocket mandrel, that has a longitudinal flow passageway in which to place it. Flow of hot water and vapor could then be diverted percentage-wise by the impingement means into the ports provided in the downhole tool or on through the longitudinal flow passageway to other downhole equipment. 
     It is therefore one object of the present invention to provide an apparatus for enhanced oil recovery by steam injection. 
     It is a further object of this invention to provide an impingement means and, if desired, an agitation means in a side pocket mandrel or other downhole tools to inject a controlled percentage of hot fluid and vapor into a formation zone. 
     It is another object of this invention to agitate and recombine multiphased steam flow in a side pocket mandrel or other downhole tools using an impingement means and, in selected embodiments, an agitation means and/or a centralizer means. 
     It is yet another object of this invention to provide a centralizer means or an agitation means in a side pocket mandrel or other downhole tools that will also guide tools through the impingement means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B taken together constitute a longitudinal view, in section, showing the side pocket mandrel with a centralizer means, an impingement means and a valve means. 
     FIG. 2 is a longitudinal view, in section, showing an impingement means constructed in accordance with the present invention. 
     FIG. 3 is a top view of FIG. 2. 
     FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 1A showing a centralizer means located in the side pocket mandrel. 
     FIG. 5 is a cross-sectional view taken along line 5--5 of FIG. 1B showing the top view of an impingement means and a valve means seated in its pocket in the side pocket mandrel. The chamber formed between the outside diameter of an impingement means and the wall of the longitudinal flow passageway of the side pocket mandrel is also shown. 
     FIG. 6 is a cross-sectional view taken along line 6--6 of FIG. 1B showing the relationship of a port means, shown as holes, in the wall of an impringement means and the ports in the valve means in the valve pocket. 
     FIG. 7 is a longitudinal view, partly in section and partly in elevation, showing an agitation means as placed in an alternate embodiment of the invention. 
     FIG. 8 is a longitudinal view, partly in section and partly in elevation, showing a side pocket mandrel of a different design than that shown in FIGS. 1A and 1B. 
     FIG. 9 is a cross-sectional view taken along line 9--9 of FIG. 8 showing an oval or eliptical shaped mandrel configuration and the chamber formed between the outside diameter of an impingement means and the wall of the longitudinal flow passageway of this design side pocket mandrel. 
     FIG. 10 is a cross-sectional view taken along line 10--10 of FIG. 8 showing a round shaped mandrel configuration and the chamber formed between the outside diameter of an impingement means and the wall of the longitudinal flow passageway of this design side pocket mandrel. 
     FIG. 11 is a longitudinal view, partly in section and partly in elevation, showing an alternative embodiment of the invention with an agitation means placed in the belly of the side pocket mandrel. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1A and 1B, the side pocket mandrel 20 may have various round or nonround cross-sectional shapes. Although many cross-sectional configurations are available to one skilled in the art of side pocket mandrel design, the shapes most used are round, oval and elliptical. Two of these shapes are shown in FIGS. 9 and 10 which are examples of possible cross-sections of the side pocket mandrel shown in FIG. 8. 
     An upper crossover sub (not shown) with threads compatible with upper side pocket mandrel body thread 31 may be used to connect the crossover sub to the side pocket mandrel 40 if centralizer means 21 is not used. The crossover sub would also contain a thread similar to upper centralizer means thread 30 that would connect side pocket mandrel 20, by means of the upper crossover sub, to a source of pressurized steam (not shown). 
     As shown in FIGS. 1A and 1B, the centralizer means 21 is connected at one end to a source of pressurized steam by upper centralizer means thread 30 and is connected to one end of the side pocket mandrel body 40 by lower centralizer means thread 32 which is mated to upper side pocket mandrel body thread 31. This is another example of possible means to connect side pocket means 20 to a source of pressurized steam. The impingement means 22 is connected to the other end of the side pocket mandrel body 40 by the upper impingement means thread 34 mated with lower side pocket mandrel body thread 33. The lower impingement means thread 35 and thereby side pocket mandrel 20 can be connected to other downhole well equipment (not shown). One skilled in the art would realize that other connecting methods other than threads could be used. 
     Pressurized steam enters the centralizer means 21. Centralizer means 21 contains a second mandrel means 60 having a third longitudinal flow passageway 63 therethrough. The third longitudinal flow passageway 62, through which the steam flows, has its inner diameter reduced to form the venturi means 61 as shown in FIG. 1A. The venturi means 61 serves at least two functions. It provides for guidance of tools through the side pocket mandrel 20 and causes a pressure change and dispersion of the steam that passes through the venturi means 61. 
     The steam then enters side pocket mandrel body 40 by way of the first longitudinal flow passageway 41. As the steam flows from its source, it tends to form laminae (not shown) of various combinations of vapor and hot fluid. The recombination or remixing of the various phases and laminae of the steam is further accomplished by impingement means 22. 
     The impingement means 22 is shown in place in side pocket mandrel 20 in FIG. 1B, in an enlarged view in FIG. 2 and is shown in a top view in FIG. 3. The impingement means 22 includes a first mandrel means 50 having a second longitudinal flow passageway 51 therethrough and a helical directing means 52 which, in the preferred embodiment, is a set of spirally cut lands 91 and grooves 92 formed on the outside diameter 58 of the first mandrel means 50. The helical directing means 52 could be a set of threads of which several different configurations are available. Also included in the impingement means 22 is longitudinal directing means 53 which includes alternating fingers 54 and slots 55 on one end of the first mandrel means 50. In FIG. 2, a second port means 56, shown as holes through the wall of the first mandrel means 50, allows communication of steam between the second longitudinal flow passageway 51 and the first longitudinal flow passageway 41. Referring to FIGS. 5 and 6, the impingement means 22 also includes a third port means 57 for draining steam from the chamber 42 formed between the wall of the first longitudinal flow passageway 41 and the outer diameter 58 of the first mandrel means 50. The steam from chamber 42 flows back into second longitudinal flow passageway 51 of first mandrel means 50 through third port means 57 and out of side pocket mandrel 20. 
     As the laminae of hot fluid and vapor form of the surfaces of the equipment above impingement means 22, vapor also flows as a more or less separate phase down through the center of the longitudinal flow passageways. The laminae of hot fluid and vapor strike the fingers 54 and the slots 55 of the longitudinal directing means 53. The laminae of hot fluid and vapor are diverted or directed through slots 55 into chamber 42 and into the spirally cut lands 90 and grooves 91 of the helical directing means 52. As the vapor phase of the steam enters the second longitudinal flow passageway 51, part of the vapor enters chamber 42 and helical directing means 52 by way of the second port means 56. Part of the vapor is deflected into the second longitudinal flow passageway 51 by fingers 54 and continues to flow out of the side pocket mandrel 20 through the second longitudinal flow passageway 51 of impingement means 22. 
     As the laminae of hot fluid and vapor are directed helically around impingement means 22 and through chamber 42 by the helical directing means 52, the laminae meet and are mixed with the vapor phase of the steam entering the helical directing means 52 and the chamber 42 through second port means 56. 
     The shape, number and configuration of the fingers 54 and slots 55 of the longitudinal directing means 53; the size of the chamber 42; the number, location and size of second port means 56; the size and configuration of the lands 91 and grooves 92 of helical directing means 52; the size of first mandrel means 50; and the size, number and location of third port means 57 affect the quality or percentage of hot fluid to vapor that is mixed in chamber 42 and enters the fourth port means 45 once the hot fluid and vapor reaches the impingement means 22. 
     Communication from chamber 42 to valve pocket 44 is accomplished by the steam passing through fourth port means 45. The amount of steam entering first port means 46 is controlled by valve means 24 located in valve pocket 44. 
     Valve means 24 is comprised mainly of latch means 80, control means 81, seal means 82 and flow direction means 83. Latch means 80 allows for placement, removal and replacement of the valve means 24 by downhole wireline tools (not shown) familiar to those skilled in the art of placing and retrieving equipment with standard latch means. Valve means 24 is similar in construction to the chemical injection valve shown on page 6238 of the Otis Engineering Corporation section of the 1984-85 Edition of The World Oil Composite Catalog. The seal means 82 and the flow direction means 83 prevent the steam from entering the valve pocket 44 by any other path other than fourth port means 45 or leaving by any other path than first port means 46 by way of flow direction means 83. Flow direction means 83 can by a one-way valve to allow flow of steam in only one direction. Valve means 24 can be installed without flow direction means 83. First port means 46 could be fitted with a means to direct the flow of steam or with a venturi means to expand and dispense the steam. The steam is now able to enter the formation after passing through the perforations (not shown). 
     Other factors influencing the percentage or quality of the steam arriving at the first port means 46 include the quantity and quality (percentage of hot fluid to vapor) available at the side pocket mandrel 20 and the influences equipment above impingement means 22 has on the steam. In alternative embodiments of the invention, a centralizer means 21 and/or an agitation means 23 are utilized in the side pocket mandrel 20. 
     The centralizer means 21, previously discussed, may be placed in the side pocket mandrel body 40 in lieu of a crossover sub (not shown). The agitation means 23 can also be placed in the same location in the side pocket mandrel body 40 just as was the centralizer means 21. One of the alternative embodiments showing the agitation means 23 in place is shown in FIG. 7. Another alternative embodiment showing the agitation means 123 is shown in FIG. 11. 
     Referring to FIG. 7, agitation means 23 is comprised mainly of third mandrel means 70, fourth longitudinal flow passageway 71 and one or more sets of interior lands 72 and grooves 73. The sets of interior lands 72 and grooves 73 may be any design of land or groove familiar to those skilled in the art and, as shown in FIG. 7, may be helically-cut and threadlike in construction. They may also alternate in the direction of their spiral as shown in FIG. 7 or may be cut in the inside diameter of third mandrel means 70 in only one direction. Third mandrel means 70 is connected to side pocket mandrel body 40 by lower agitation means thread 36 which mates with upper side pocket mandrel body thread 31. Upper agitation means thread 37 is the means for connecting the other end of the third mandrel means 70 to the source of pressurized steam. 
     The agitation means 23 amalgamates the hot fluid and vapor in preparation for entering the impingement means 22 where the steam is further blended. As steam enters the third longitudinal flow passageway 62, the laminae of hot fluid and vapor are agitated by the lands 72 and the grooves 73 by turbulence and also by the alternating direction of flow caused by the reversed direction of the spiral formed by the lands 72 and grooves 73. The amalgamated steam then flows through the first longitudinal flow passageway 41 and on to the impingement means 22 as described above. The third mandrel means 70 may also be designed to provide guidance of tools through the side pocket mandrel 20 and especially through impingement means 22. 
     An alternative embodiment of side pocket mandrel 20 is side pocket mandrel 120 shown in FIG. 11. The flow and blending of steam to be provided to the formation is accomplished in much the same manner as the other embodiment except that the agitation means 121 is located lower in first longitudinal flow passageway 141 than the agitation means 23 was in first longitudinal flow passageway 41 shown in FIG. 7. This embodiment allows centralizer means 121, which is identical to centralizer means 21, to be utilized with agitation means 123. Centralizer means 123 is attached to side pocket mandrel body 140 in the same manner as described for centralizer means 23 in side pocket mandrel body 40. This combination of centralizer means 121 and agitation means 123 allows the user to enhance the mixing and blending of the steam if considered necessary to provide the selected or calculated quality or percentage of hot fluid and vapor to the formation. Impingement means 122 is identical to impingement means 22 and is attached to side pocket mandrel body 140 in the same manner as described for agitation means 22 in side pocket mandrel body 40. 
     The foregoing descriptions and drawings of the invention are explanatory and illustrative only, and various changes in shapes, sizes and arrangements of parts as well as certain details of the illustrated construction may be made within the scope of the appended claims without departing from the true spirit of the invention.